The basis for immunotherapy is the manipulation of the immune system, including both innate immune responses and adaptive immune responses. The aim of immunotherapy is to treat diseases by controlling the immune response to a “foreign agent”, for example a pathogen or a tumor cell. This may include methods to induce or enhance specific immune responses or to inhibit or reduce specific immune responses. The immune system is a highly complex system made up of a great number of cell types, including, T-cells, B-cells, natural killer cells, antigen-presenting cells, dendritic cells, monocytes, and macrophages. These cells possess complex and subtle systems for controlling their interactions, including utilizing numerous receptors and soluble factors for the process. The cells utilize both activating and inhibitory mechanisms to keep responses in check and not allow negative consequences of an uncontrolled immune response (e.g., autoimmune diseases).
The concept of cancer immunosurveillance is based on the theory that the immune system can recognize tumor cells, mount an immune response, and suppress the development and/or progression of a tumor. However, it is clear that many cancerous cells have developed mechanisms to evade the immune system allowing the uninhibited growth of tumors. Cancer immunotherapy focuses on the development of agents that can activate and/or boost the immune system to achieve a more effective response to killing tumor cells and inhibiting tumor growth.